1. Field of the Invention
The present invention relates to a vehicle air handling system that includes a moisture absorbing desiccant assembly. More specifically, the present invention relates to a vehicle air handling system where a moisture absorbing desiccant assembly includes a moisture absorbing section and a moisture releasing section.
2. Background Information
Vehicle air conditioning systems have been used in vehicles for many years and are continuously being improved. Such systems typically include a conventional compressor that compresses low pressure refrigerant into high pressure refrigerant, a condenser that dissipates heat (and energy) from the high pressure refrigerant, an expansion valve or similar throttling device that allows the high pressure refrigerant to expand (and thereby become low pressure refrigerant) and an evaporator that allows the low pressure refrigerant to absorb heat from a confined space such as the passenger compartment of the vehicle.
Such air conditioning systems also typically include an air handling mechanism that treats the airflow passing therethrough. For example, the air handling mechanism may include a fan or blower that directs airflow through the air handling mechanism. The air handling mechanism can include the evaporator of the air conditioning system. The airflow through the air handling mechanism can then be cooled as it passes by coils of the evaporator. As the airflow passes by the evaporator, moisture also condenses on the surfaces of the evaporator.
Typically during operation of the vehicle air conditioning system, it is possible to direct a selected portion or all of re-circulated air from within the passenger compartment along with a selected portion of ambient fresh air from outside the vehicle to flow into the air conditioning system. This mix of ambient air and re-circulated air defines the airflow passing through the air handling mechanism.
Regardless of the source of the airflow (re-circulated air or fresh ambient air), moisture in the airflow condenses on the surfaces of the evaporator coils. The energy consumed by the condensation of moisture on the surfaces of the evaporator is measurable. If the airflow is heavily laden with moisture (a high level of humidity), then the air conditioning system consumes a large portion of energy on removing the moisture rather than cooling the airflow. The consumption of energy is considerable and has a direct relationship with the potential energy efficiency of the air conditioning system. In order to improve the energy efficiency of the vehicle air conditioning system, it is advantageous to reduce the amount of moisture in the airflow prior to passage over the cooling surfaces of the evaporator.
Many air conditioning systems with moisture reducing devices have been proposed in recent years, including systems that use a desiccant material that absorbs moisture upstream from the evaporator. One such system is described in U.S. Pat. No. 5,327,739 to Ingersoll et al. that includes a desiccant chamber with a heater that drives off absorbed water. The desiccant chamber absorbs moisture but when the desiccant chamber becomes saturated with moisture, the heater must be turned on. While the heater is turned on, the desiccant chamber cannot be used. Thus, the system disclosed by Ingersoll et al. cannot continuously absorb moisture from the airflow passing through the disclosed system.
Other air conditioning systems that include desiccant materials require routine replacement of the desiccant material once the desiccant material becomes saturated with moisture.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle air conditioning system that uses a desiccant material that can be used continuously without interruption and that does not require routine replacement. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.